can someoe explain these lines

[dreadylock 0]

hi i keep getting lines in my model when previewing in Cura is this a problem because their not in my model

[fvrmr 73]

Hi @dreadylock do you mean the blue lines around your model? This is the brim, which is for better adhesion of your print. 

You can edit this in the build plate adhesion type setting. 

Let me know if that is what you mean!

[GregValiant 1,141]

@fvrmr, I believe he is referring to the outer wall lines and skins that are 1 layer thick.

 

This occurs in some models with certain CAD softwares (but not often).  I personally think they are leftover artifacts from changes that were made to the model during it's design, but the cause hasn't really been nailed down.  They are generally 1 layer thick.  Going back to the design software and cleaning it up works.  You might be able to adjust the layer height in Cura to get rid of them.

You can see that the little triangle area that touches the hole in the first image is definitely 1 layer below the main surface.  I know it's annoying but you have to admit - Cura does a fine job of picking up subtle features.

 

Also - looking at the length of the chord segments around the arc (if it is indeed a circular feature) indicates that the model was exported from CAD with a very low resolution.  Maybe increasing the resolution of the STL generator in the CAD software would make a difference.